Sealing rings of the above-mentioned type are used particularly for the coupling of sewer pipes, or in general pipes for the discharge of effluent, which are dug in to below ground level and can therefore lie below groundwater level, so that the sealing rings have to be capable of sealing not only relative to an internal, but also relative to an external excess pressure.
In the case of the known sealing ring, when the push-in end part of a pipe is being inserted into the ring the single lip present there is pressed against the supporting ring, so that said lip is compressed between the external surface of the push-in end part and the supporting ring.
The disadvantage of the known sealing ring is that in order to bring about the coupling between two pipes in which the push-in end part of one pipe must be pushed through the sealing ring fitted in the other pipe great axially directed forces must be exerted, which makes the production of the pipe coupling unacceptably difficult. Besides, in the coupling which has been made the seal relative to an external excess pressure leaves something to be desired.